I could interest you could interest he could interest we could interest you could interest they could interest
V-ing form
I could be interesting you could be interesting he could be interesting we could be interesting you could be interesting they could be interesting
Perfect
I could have interested you could have interested he could have interested we could have interested you could have interested they could have interested
V-ing perfect
I could have been interesting you could have been interesting he could have been interesting we could have been interesting you could have been interesting they could have been interesting
Negation
Simple form
I couldn't interest you couldn't interest he couldn't interest we couldn't interest you couldn't interest they couldn't interest
V-ing form
I couldn't be interesting you couldn't be interesting he couldn't be interesting we couldn't be interesting you couldn't be interesting they couldn't be interesting
Perfect
I couldn't have interested you couldn't have interested he couldn't have interested we couldn't have interested you couldn't have interested they couldn't have interested
V-ing perfect
I couldn't have been interesting you couldn't have been interesting he couldn't have been interesting we couldn't have been interesting you couldn't have been interesting they couldn't have been interesting
Interrogative form
Simple form
could I interest? could you interest? could he interest? could we interest? could you interest? could they interest?
V-ing form
could I be interesting? could you be interesting? could he be interesting? could we be interesting? could you be interesting? could they be interesting?
Perfect
could I have interested? could you have interested? could he have interested? could we have interested? could you have interested? could they have interested?
V-ing perfect
could I have been interesting? could you have been interesting? could he have been interesting? could we have been interesting? could you have been interesting? could they have been interesting?
Interro-negative form
Simple form
couldn't I interest? couldn't you interest? couldn't he interest? couldn't we interest? couldn't you interest? couldn't they interest?
V-ing form
couldn't I be interesting? couldn't you be interesting? couldn't he be interesting? couldn't we be interesting? couldn't you be interesting? couldn't they be interesting?
Perfect
couldn't I have interested? couldn't you have interested? couldn't he have interested? couldn't we have interested? couldn't you have interested? couldn't they have interested?
V-ing perfect
couldn't I have been interesting? couldn't you have been interesting? couldn't he have been interesting? couldn't we have been interesting? couldn't you have been interesting? couldn't they have been interesting?